JP2002110563A - Model creating method for heat treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create and calibrate a mathematical model for estimating the temperature of an object to be processed. SOLUTION: With respect to heat treatment apparatuses having different thermal characteristics from each other, there are created previously their mathematical models for estimating the temperatures of objects to be processed mounted in their heating furnaces. When manufacturing newly a heat treatment apparatus, it is specified that which heat treatment apparatus of the plural ones whose mathematical models have been prepared previously is analogous to the objective one whose mathematical model is created (step S2). Then, while using the mathematical model of the specified heat treatment apparatus and estimating the temperature of its object to be processed, the heat treatment of its object to be processed is performed (step S4). By measuring the film thickness of a film formed actually (step S5) and by comparing the film thickness with the desired value thereof (step S6), the mathematical model of the specified heat treatment apparatus is modified to perform a desired heat treatment according to the compared result (step S7). By repeating this processing, a fundamental mathematical model is calibrated to create the mathematical model for an individual heat treatment apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention estimates the temperature of an object to be processed such as a semiconductor wafer in a non-contact manner using a mathematical model,
The present invention relates to an adaptive control type batch heat treatment apparatus that performs optimal control based on an estimation result.

[0002]

2. Description of the Related Art U.S. Pat. No. 5,517,594 discloses a batch type heat treatment apparatus for estimating the temperature of a semiconductor wafer using a mathematical model. conventionally,
One heat treatment device (one model; heat treatment device with the same design)
, One basic mathematical model (basic model) was created, and individual devices were actually operated to fine-tune the mathematical model.

[0003]

However, in this method, a basic model must be created for each type of heat treatment apparatus, and the design of the basic model is difficult. The present invention has been made in view of the above situation, and has as its object to facilitate the design of a mathematical model of a heat treatment apparatus.

[0004]

In order to achieve the above object, a method for generating a model of a heat treatment apparatus according to a first aspect of the present invention has a different configuration from each other, and comprises a plurality of heaters and a plurality of temperature sensors. A plurality of heat treatment apparatuses that estimate a temperature of an object to be processed in the heating furnace based on an output of the temperature sensor and control the plurality of heaters according to the estimated temperature. A mathematical model for estimating the temperature of the object to be processed in the heating furnace is prepared based on the output of the heating furnace, and a heat treatment apparatus for creating the mathematical model is a plurality of heat treatment apparatuses in which the mathematical model is prepared in advance. Using a mathematical model for the specified heat treatment apparatus, heat treatment is performed while estimating the temperature of the object to be processed, and the film thickness of the actually formed film and the target The comparator compares the value, according to the comparison result, as desired heat treatment is carried out, by modifying the mathematical model, to create a mathematical model for the heat treatment apparatus, characterized in that.

According to this configuration, it is not necessary to independently create a mathematical model for measuring the temperature of the object to be processed for each of the heat treatment apparatuses, and it is possible to cope only by modifying the existing mathematical model. Therefore, the burden of creating a mathematical model can be reduced as compared with the case where a new mathematical model is created.

In order to achieve the above object, a second aspect of the present invention is provided.
A method for generating a model of a heat treatment apparatus according to the aspect of the present invention includes a heating furnace that includes a plurality of heaters and a plurality of temperature sensors, and accommodates an object to be processed inside the heating furnace, based on an output of the temperature sensor. A memory that stores a model for estimating the temperature of the processing object, and based on the model stored in the memory, estimates the temperature of the processing object from the output of the temperature sensor, and according to the estimated temperature, A method for generating a model of a plurality of heat treatment apparatuses, comprising: a controller that controls a plurality of heaters, wherein the plurality of heat treatment apparatuses having different hardware configurations belong to one group. And allocating a basic mathematical model to each group. For each heat treatment apparatus, the output of the temperature sensor and the heat treatment apparatus From the mathematical model assigned to the group to which it belongs, heat treatment is performed while estimating the temperature of the object to be processed, and the thickness of the actually formed film is compared with the target value. Modifying the mathematical model or correcting the estimated temperature using the mathematical model as performed.

According to this configuration, if a mathematical model is created for each group, it is not necessary to create a mathematical model for each heat treatment apparatus, and it is possible to cope only by modifying the mathematical model for the group. Therefore, the burden of creating a mathematical model can be reduced as compared with the case where a new mathematical model is created.

In the method of generating a mathematical model according to the first and second aspects, for example, when the thickness of an actually formed film is smaller than a target value, the estimated temperature is reduced. When the film thickness of the actually formed film is larger than the target value, the mathematical model is corrected so that the estimated temperature becomes higher.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for creating a mathematical model for a batch type heat treatment apparatus according to the present invention will be described.
Heat treatment equipment has various hardware configurations,
From the hardware configuration, it can be classified into a plurality of groups including heat treatment apparatuses having similar thermal characteristics. Therefore, in the present embodiment, known heat treatment apparatuses are classified into several groups based on their basic configuration or thermal characteristics. For example, FIG. 1 shows a certain group (hereinafter group A).
1 shows a basic structure of a vertical heat treatment apparatus belonging to. This vertical heat treatment apparatus includes a reaction tube 2 having a double tube structure including an inner tube 2a and an outer tube 2b made of quartz, and a metal cylindrical manifold 21 is provided below the reaction tube 2. Have been.

In the reaction tube 2, a large number, for example, 150
A plurality of wafers W (product wafers) constituting a processing object are horizontally arranged in a shelf shape on a wafer boat 23 as a wafer holder with a vertical interval. This wafer boat 2
3 is held on a lid 24 via a heat insulating cylinder (heat insulating body) 25.

A heater section 3 is provided around the reaction tube 2. The heater unit 3 includes heaters 31 arranged in five stages.
~ 35. Electric power is supplied to the heaters 31 to 35 independently from the electric power controllers 36 to 40. A heating furnace is constituted by the reaction tube 2, the manifold 21, and the heater unit 3.

Further, three gas supply pipes 41, 42, and 43 are provided in the manifold 21 so as to supply gas into the inner pipe 2a.
43 are arranged. Each gas supply pipe 41, 42, 43
Is supplied with a source gas, a carrier gas, and the like via flow rate adjustment units 44, 45, and 46 such as a mass flow controller (MFC) for adjusting a gas flow rate. Further, an exhaust pipe 27 is connected to the manifold 21. The exhaust pipe 27 is connected to a vacuum pump (not shown). The exhaust pipe 27 is provided with a pressure adjusting unit 28 for adjusting the pressure in the reaction tube 2.

On the inner surface of the inner tube 2a, 5
Two thermocouples (temperature sensors) Sin1 to Sin5 are arranged. The thermocouples Sin1 to Sin5 are covered with, for example, a quartz pipe or the like in order to prevent metal contamination of the semiconductor wafer W, and are respectively arranged in five zones illustrated in FIG.

On the outer surface of the outer tube 2b, a plurality of thermocouples (temperature measuring units) Sout1 to Sout5 are arranged in a line in the vertical direction. The thermocouples Sout1 to Sout5 are also arranged in five zones exemplified in FIG.

The vertical heat treatment apparatus includes a control unit (controller) 100 for controlling processing parameters such as the temperature, gas flow rate, and pressure of the processing atmosphere in the reaction tube 2. The control unit 100 includes thermocouples Sin1 to Sin5 and Sout1.
To the power controllers 36 to 40 of the heaters 31 to 35, the pressure adjusting unit 28, and the flow rate adjusting units 44 to 46.

FIG. 2 shows the configuration of the control unit 100. As illustrated, the control unit 100 includes a model storage unit 111,
Recipe storage unit 112, ROM 113, RAM 114
, An I / O port 115, a CPU 116, and a bus 117 interconnecting these components.

The model storage unit 111 stores thermocouples Sin1 to Si
In order to estimate (calculate) the temperature of the wafer W placed on the wafer boat 23 from the output signals (measured temperature) of n5 and Sout1 to Sout5 and the output of the power controller, and to further change the estimated temperature to a target value. Heaters 31-35
A mathematical model (higher-order / multidimensional function) for indicating a current (power) to be supplied to the power supply is stored for each temperature band.

The recipe storage unit 112 stores a recipe that determines a control procedure according to the type of heat treatment (for example, a film forming process) performed by the heat treatment apparatus. Each recipe includes a temperature recipe (a target value of a temperature change to be processed by the wafer W to be processed; a target temperature trajectory). In the case of normal batch processing, one type of heat treatment (for example, film formation processing)
For, one temperature recipe is prepared for all wafers. On the other hand, in this embodiment, FIG.
As shown in FIG. 3B, for five zones exemplified in FIG. 3A, temperature recipes (target temperature trajectories) adjusted for each zone are prepared. The temperature recipe adjusted for each zone is adjusted so that variations in film thickness due to factors such as gas flow rates and concentration differences can be absorbed (canceled) by temperature control.

The ROM 113 includes an EEPROM, a flash memory, a hard disk, and the like.
It is a recording medium for storing 16 operation programs and the like.

The RAM 114 functions as a work area for the CPU 116 and the like. The I / O port 115 transmits measurement signals of the thermocouples Sin1 to Sin5 and Sout1 to Sout5 to the CPU.
The control signal is supplied to the CPU 116 and the control signal output from the CPU 116 is output to each unit. An operation panel 118 is connected to the I / O port 115. Bus 117
Communicates information between the parts.

The CPU 116 may be constituted by a DSP or the like, operates according to a control program stored in the ROM 113, responds to an instruction from the operation panel 118,
According to the recipe stored in the recipe storage unit 112,
The operation of the heat treatment device is controlled. Specifically, the CPU 11
6 reads the model stored in the model storage unit 111 and executes a processing operation according to the recipe stored in the recipe storage unit 112.

The CPU 116 also issues an instruction to the flow rate adjusting units 44 to 46, an instruction to the pressure adjusting unit 28, and the like, similarly to the control of a normal heat treatment apparatus.

On the other hand, the vertical heat treatment apparatus shown in FIG. 4 shows a basic configuration of a heat treatment apparatus belonging to a heat treatment apparatus group (hereinafter, group B) having heat characteristics different from those of a heat treatment apparatus belonging to group A. This heat treatment apparatus includes a reaction tube 2 having a single tube structure. A gas supply pipe 41 is connected to the ceiling of the reaction pipe 2. A manifold 21 to which a gas exhaust pipe 27 is connected is provided below the reaction tube 2. Around the reaction tube 2, heaters 31 to 33 controlled by power controllers 36 to 38 are provided. Further, thermocouples Sin1 to Sin3 are provided on the inner surface of the reaction tube 2, and thermocouples Sout1 to Sin3 are provided on the outer surface.
out3 is located.

This heat treatment apparatus also has a control unit having a configuration similar to the configuration shown in FIG. However, the model storage unit 111
Estimates (calculates) the temperature of the wafer W placed on the wafer boat 23 from the output signals (measured temperatures) of the thermocouples Sin1 to Sin3 and Sout1 to Sout3, and sets the estimated temperature to a target value. Therefore, a mathematical model designed to indicate the current (power) to be supplied to the heaters 31 to 33 is stored for each temperature band.

The method of creating the mathematical model (basic model) for the heat treatment apparatus shown in FIGS. 1 and 4 is similar to the method disclosed in, for example, US Pat. No. 5,517,594.

Next, a method of designing a mathematical model of an arbitrary heat treatment apparatus using the heat treatment apparatus and the mathematical model prepared in advance as described above will be described with reference to the procedure flow of FIG.

First, a heat treatment apparatus having hardware specifications meeting the requirements of the client is designed, and a test apparatus is manufactured (step S1). For example, according to the request of the client, the size of the reaction tube, the diameter and number of wafers mounted on the wafer boat,
Hardware such as the number of heaters and the number and diameter of gas pipes is appropriately designed to manufacture a test apparatus.

Next, it is determined whether the thermal characteristics of the test device are similar to any of the heat treatment devices for which the mathematical model has been created (step S2).

Next, a mathematical model for the heat treatment apparatus determined to be similar is stored in the model storage section 111 of the control section 100 of the test apparatus. Further, the calibration recipe prepared in advance is stored in the recipe storage unit 112 (step S3).

Next, the test apparatus is actually subjected to a heat treatment (for example, a film forming process) in accordance with a calibration recipe (step S4). Next, the thickness of the film actually formed (formed) is measured (step S5).

Further, the measured value of the film thickness is compared with the target value (step S6). If the difference between the measured value and the target value is larger than the allowable range, the mathematical model is corrected (step S6).
7).

More specifically, thermocouples Sin, S
out, a heat treatment according to a calibration recipe is performed, and the thickness of the formed film is measured while assuming the temperature of the wafer to be processed using the power supplied to each heater.

Generally, when the thickness of the formed film is smaller than the target value, the temperature during the heat treatment may be increased, and when the thickness of the formed film is larger than the target value, the temperature during the heat treatment may be increased. Temperature may be lowered. That is, in the former case, the estimated temperature of the wafer by calculation is lowered to increase the temperature at the time of heat treatment, and in the latter case, the estimated temperature of the wafer by calculation is increased by increasing the estimated temperature of the wafer. Try to lower the temperature.

Therefore, when the thickness of the formed film is smaller than the target value, correction is made so as to lower the wafer temperature calculated using the mathematical model. For example, the mathematical model is modified such that Δt (Δt is a positive value) is subtracted from the temperature Tcal calculated using the mathematical model, and Tcal−Δt is taken as the wafer temperature. Alternatively, the mathematical model is modified so that Tcal · α (α is a positive number smaller than 1) is set as the wafer temperature.

Similarly, when the thickness of the formed film is larger than the target value, the mathematical model is modified so as to increase the calculated wafer temperature. For example, Δt is added from the temperature Tcal calculated using a mathematical model, and Tcal + Δt
The mathematical model is modified so that is the wafer temperature. Alternatively, the mathematical model is modified so that Tcal · β (β is a positive number greater than 1) is set as the wafer temperature.

Next, the basic model (corrected model) corrected in this manner is stored in the model storage unit 111, and the process returns to step S4, where the heat treatment is performed again to measure the thickness of the formed film. (Step S5) Compare with the target value (Step S6). The above process is repeated, and when the difference between the thickness of the actually manufactured film and the target value of the film thickness is within the allowable range, the design of the mathematical model is completed.

When it is determined that the newly designed heat treatment apparatus has a configuration similar to the heat treatment apparatus as shown in FIG. 4, the mathematical model for the heat treatment apparatus shown in FIG. Create a mathematical model for the newly manufactured heat treatment equipment.

According to such a mathematical model creation method,
It is not necessary to create models individually from the beginning for all heat treatment equipment, and for heat treatment equipment of the same specification,
If one mathematical model is created in advance, a mathematical model can be created by calibrating the model for each device, and the creation and tuning of the mathematical model can be performed efficiently.

In the above description, a case has been described in which a plurality of heat treatment apparatuses having a mathematical model that is known in advance and has been calibrated are present, but the present invention is not limited to this example. For example, when newly designing and manufacturing a plurality of heat treatment apparatuses, the heat treatment apparatuses to be designed are classified into a plurality of groups, and one basic heat treatment apparatus is specified in each group.
A mathematical model may be created for this, and the other heat treatment apparatuses may be used by calibrating the mathematical model for the basic heat treatment apparatus in the same group.

[0040]

As described above, according to the present invention, a mathematical model of a heat treatment apparatus can be appropriately and easily created.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the structure of a heat treatment apparatus.

FIG. 2 is a circuit diagram illustrating a configuration example of a control unit.

3A is a diagram showing a zone in a reaction tube, and FIG. 3B is a diagram showing an example of a target temperature trajectory for each zone.

FIG. 4 is a diagram showing another example of the structure of the heat treatment apparatus.

FIG. 5 is a flowchart for explaining a mathematical model design process.

[Explanation of symbols]

 2 Reaction tube 3 Heater section 21 Manifold 23 Wafer boat 24 Lid 25 Heat insulation cylinder (insulation body)

Continued on the front page (72) Inventor Wang Ling, 1-2-4, Machiya, Shiroyama-cho, Tsukui-gun, Kanagawa Prefecture Inside the Sagami Office of Tokyo Electron Tohoku Co., Ltd. (72) Inventor Moyuru Yasuhara 5-chome Akasaka, Minato-ku, Tokyo No. 6 Tokyo Electron Co., Ltd. F term (reference) 4K056 AA09 FA04 FA13 5F045 BB01 DP19 EK07 EK25 GB01 GB05 GB13 GB16 GB17 5H004 GB15 HA01 HA06 HB01 JA04 JA12 JA22 JB08 KA71 KC28 LA18

Claims (3)

[Claims] And a heating furnace having a plurality of temperature sensors, each of which is configured to estimate a temperature of an object in the heating furnace based on an output of the temperature sensor. A plurality of heat treatment apparatuses for controlling the plurality of heaters in accordance with the estimated temperature, respectively preparing a mathematical model for estimating a temperature of an object to be processed in the heating furnace based on an output of the temperature sensor; The heat treatment apparatus for which the model is to be created specifies which of the plurality of heat treatment apparatuses in which the mathematical model is prepared in advance, and the temperature of the object to be processed is determined using the mathematical model for the specified heat treatment apparatus. The heat treatment is performed while estimating, the thickness of the actually formed film is compared with the target value, and the mathematical model is modified according to the comparison result so that the desired heat treatment is performed. Forming a mathematical model for the heat treatment apparatus. 2. A heating furnace which includes a plurality of heaters and a plurality of temperature sensors, and accommodates an object to be processed therein, and estimates the temperature of the object within the heating furnace from an output of the temperature sensor. And a control for estimating the temperature of the object from the output of the temperature sensor based on the model stored in the memory, and controlling the plurality of heaters according to the estimated temperature. A controller,
A model generation method for a plurality of heat treatment apparatuses comprising: a plurality of heat treatment apparatuses having different hardware configurations from each other;
The heat treatment devices having similar temperature characteristics are classified into a plurality of groups so as to belong to one group, and a basic mathematical model is assigned to each group. For each heat treatment device, the output of the temperature sensor and the group to which the heat treatment device belongs The heat treatment is performed while estimating the temperature of the object to be processed from the mathematical model assigned to the object, and the thickness of the actually formed film is compared with the target value, and the desired heat treatment is performed according to the comparison result. Modifying the mathematical model or modifying the temperature estimated using the mathematical model as described above. 3. When the film thickness of the actually formed film is smaller than the target value, the mathematical model is modified so that the estimated temperature becomes lower, and the film thickness of the actually formed film becomes smaller. The model generation method according to claim 1, wherein when the thickness is larger than the target value, the mathematical model is corrected so that the estimated temperature becomes higher.